char * longestCommonPrefix(char ** strs, int strsSize){
    if (strsSize == 0) return "";
    char *prefix = strs[0];
    for (int i = 1; i < strsSize; i++) {
        int j = 0;
        while (prefix[j] && strs[i][j] && prefix[j] == strs[i][j]) j++;
        prefix[j] = '\0';
    }
    return prefix;
}
